Liver & Pancreas

Question 1

How do pancreatic secretions travel to the duodenum?

Answer 1

Pancreatic duct –> common bile duct –> sphincter of Oddi

Question 2

What percentage of the pancreas has an endocrine function?

Answer 2

1-2%

Question 3

Which salivary gland does the exocrine pancreas resemble?

Answer 3

Parotid

Question 4

How many enzymes are formed by the pancreas for digestion?

Answer 4

15

Question 5

Where are the nuclei in pancreatic enzyme producing cells?

Answer 5

At the base

Question 6

What is the structure of the exocrine glands in the pancreas and what type of secretion occurs here?

Answer 6

Branched acinar

Merocrine (into a central cavity)

Question 7

What are centroacinar cells?

Answer 7

Cells that partially line lumen of acinus/duct

Secrete HCO3-

Question 8

How can you tell the difference between acinar and centroacinar cells?

Answer 8

Nuclei are at the centre in centroacinar cells and at the base in acinar cells

Question 9

What is different about the ducts of salivary glands and the exocrine pancreas?

Answer 9

No striated ducts in the pancreas

Question 10

What do the islets of Langerhans look like?

Answer 10

Pale-staining, small with profuse blood supply

Question 11

What is produced by the islets of Langerhans?

Answer 11

Insulin

Glucagon

Somatostatin

Vasoactive intestinal peptide VIP

Pancreatic polypeptide PP

Question 12

How are the cells arranged in the islets of Langerhans?

Answer 12

Arranged in columns/cords around a capillary

Question 13

Why are pancreatic enzymes secreted in proenzyme form?

Answer 13

Prevent self-digestion

Question 14

What are the eight functions of the liver?

Answer 14

Exocrine - produce bile for duodenum

Process absorbed nutrients

Metabolism of carbohydrates, fats and protein

Involved in storage of carbohydrates, fats and vitamins

Synthesise and secrete plasma proteins and lipoproteins

Detoxification of ingested toxins, drugs

Destroys old RBCs and reclaims iron

First site of haematopoiesis in the embryo

Question 15

How many lobules are in a human liver and what shape are they?

Answer 15

1 million

Hexagonal

Question 16

Why are the lobules of the liver hard to distinguish in humans?

Answer 16

Less connective tissue between

Question 17

How does the processed blood of a lobule enter the hepatic vein?

Answer 17

Sinusoids deliver to the central vein (of that lobule)

Question 18

What are portal tracts?

Answer 18

Triad at vertices of liver lobules

Consist of a branch of:

• Hepatic portal vein (largest)
• Hepatic artery
• Bile duct

Question 19

What does the hepatic portal vein do?

Answer 19

Delivers blood containing nutrients from small intestine to the liver

Question 20

What does the hepatic artery do?

Answer 20

Delivers oxygenated blood to the hepatocytes/liver

Question 21

What does the bile duct do?

Answer 21

Collects bile produced by hepatocytes

Question 22

Which way does blood and bile flow in a lobule?

Answer 22

Blood = towards central vein

Bile = away from central vein

Question 23

How are the hepatocytes arranged in the lobules and what do they look like?

Answer 23

Rows with sinusoids between; 1-2 layers of cells

Roughly cuboidal with microvilli

Question 24

Describe the sinusoids of the liver.

Answer 24

Discontinuous and fenestrated endothelial cell lining

2-3 RBC diameter

Contain Kupffer cells

Question 25

What is the function of the Kupffer cells?

Answer 25

Phagocytic - take up pathogens and particulate material

Question 26

Where is the space of Disse?

Answer 26

Between endothelial cell lining of sinusoids and surface/microvilli of hepatocytes

Question 27

What are the alternative names for Ito cells?

Answer 27

Hepatic stellate cells Perisinusoidal cells

Question 28

What is the function of Ito cells?

Answer 28

Store vitamin A in lipid droplets

Question 29

Where are Ito cells found?

Answer 29

Space of Disse

Question 30

How can Ito cells cause liver cirrhosis?

Answer 30

Inflammatory stimuli (eg. alcohol) can cause Ito cells to transform into myofibroblasts Produce large amounts of collagen and ECM Blocks blood/nutrient flow across lobule Hepatocyte death

Question 31

Why is it beneficial to have a discontinuous endothelial cell lining in the liver sinusoids?

Answer 31

Direct contact of blood with hepatocyte microvilli increases efficiency of transfer

Question 32

How is bile delivered to the bile duct from the hepatocytes?

Answer 32

Bile canaliculi --> bile duct branch of portal tract --> Bile duct

Question 33

Where are bile canaliculi found?

Answer 33

Between hepatocytes

Question 34

What do hepatocytes secrete?

Answer 34

Albumin Fibrinogen Clotting factors

Question 35

What prevents bile from moving between hepatocytes?

Answer 35

Tight junctions

Question 36

What does bile contain?

Answer 36

Bile salts Bile pigments

Question 37

What are deoxycholate, sodium glycocholate and taurocholate examples of?

Answer 37

Bile salts

Question 38

What are bile salts and what is their function?

Answer 38

Breakdown products of cholesterol Detergents to emulsify fats in duodenum

Question 39

What are the two bile pigments and what colours are they?

Answer 39

Biliruben - red Biliverdin - green

Question 40

What are bile pigments?

Answer 40

Breakdown products of haemoglobin

Question 41

What is a liver acinus?

Answer 41

Body of tissue supplied by two triads

Question 42

Which zone is the most oxygen-rich in a liver acinus?

Answer 42

Zone 1

Question 43

What zone of a liver acinus would be affected first by phosphorus and why?

Answer 43

Zone 1 Immediately toxic to hepatocytes

Question 44

What zone of a liver acinus would be affected first by paracetamol and why?

Answer 44

Zone 3 Toxic breakdown products

Question 45

Describe how paracetamol is metabolised by the liver.

Answer 45

P450 used to convert paracetamol to a reactive quinone derivative Reactive quinone derivative removed by glutathione

Question 46

What substance is used to replenish glutathione levels?

Answer 46

Methionine

Question 47

Why is an overdose of paracetamol so dangerous?

Answer 47

Glutathione supply depleted so reactive quinone derivative binds covalently to cellular proteins and kills cells Liver failure

Question 48

Why should you not ingest barbiturates and alcohol with paracetamol?

Answer 48

They induce liver enzymes which potentiates the toxicity of paracetamol

Question 49

How much bile is stored in the gall bladder usually?

Answer 49

50ml

Question 50

How does the gall bladder concentrate bile?

Answer 50

Na/K-ATPase pump on BL membrane pumps Na+ across membrane (absorbed) Water follows by osmosis

Question 51

What type of epithelium lines the gall bladder?

Answer 51

Tall, simple, columnar epithelium with irregular brush border

Question 52

Why does it look like there are cracks between the basal surfaces of adjacent cells lining the gall bladder?

Answer 52

Influx of water following NaCl pumping into interstitial space

Question 53

What stimulates the smooth muscle of the gall bladder to contract?

Answer 53

Cholecystokinin

Question 54

Where is cholecystokinin produced?

Answer 54

Cells in base of crypts of duodenum